1. Field of the Invention
The present invention relates to a device for removing loose particulates and testing lens bond strength on optical subassemblies by applying a regulated flow of nitrogen to the optical subassembly.
2. Description of the Related Art
Fiber optical systems are increasingly being used to transmit digital information over long distances in the form of light pulses because they exhibit a very large capacity for carrying information, are light-weight, and are immune to electromagnetic interference. One of the most significant components of these systems are the optical subassemblies (OSAs) which generate the light pulses, i.e. the optical signals.
The OSA includes a semiconductor laser diode, a spherical ball lens, and a monitor photodiode mounted on a silicon optical bench (siob). The fabrication of the OSA is typically divided into two parts: the mechanical assembly steps and the testing steps. During the mechanical assembly steps, the laser diode, the photodiode and the spherical lens are attached to the siob via an epoxyless attachment. Generally, a coating on the spherical lens bonds with a coating on the siob through a heating procedure after the spherical lens is placed on the siob. Ribbon bonds are then added to connect the laser diode and the photodiode to the siob.
Early manufacturing techniques for prior art OSAs were typically performed in "clean rooms" to prevent particulates from settling on the OSAs during manufacture. However, "clean rooms" are expensive to operate and maintain. Since then, hooded enclosures have been used in regular office space; the hooded enclosures are much less expensive to operate and maintain. However, hooded enclosures are not as clean as "clean rooms" and some particulates do settle on the OSAs, thereby adding an additional required step of particulate removal to the assembly process. After the OSAs, have been assembled, they are loaded onto waffle packs in groups of 50 and are then typically subjected to a flow of air in an effort to remove any loose particles. The flow of air also serves to test the bond strength between the lens and the siob. The prior art procedure for applying this flow of air uses a hand-held blower, such as an Aero-Duster.RTM.; however, a particular disadvantage of this method for removing loose particulates and for testing lens bond strength is that personnel performing the operation inconsistently apply the flow of air to the OSAs. At one extreme, this inconsistent application may result in too much air flow being applied to the waffle pack, causing one or more of the OSAs to become dislodged from the waffle pack. At the other extreme, the application of too little air flow causes inadequate removal of loose particles and inadequate testing of the bond strength of the lens.